Direct alpha to X phase conversion of metal containing phthalocyanine

ABSTRACT

Process for direct alpha to X phase conversion of metal containing phthalocyanines. In this process, the alpha polymorph of a metal containing phthalocyanine pigment can be directly converted to the X form by depositing the alpha form of the pigment on a suitable substrate followed by in situ conversion of this deposit by controlled heating. The X form of metal containing phthalocyanines are known to possess good electrophotographic speed, and, thus, can be used either alone or in combination with other photoconductive materials in electrophotography.

Griffiths et al.

DIRECT ALPHA TO X PHASE CONVERSION OF METAL CONTAINING PIITI'IALOCYANINE Inventors: Clifford I-I. Griffiths, Brighton;

Michael S. Walker, Penfield, both of A gn Xerox Corporation, Stamford, alpha polymorph of a metal containing phthalocyanine Conn. pigment can be directly converted to the X form by Filed: June 4, 1973 depositing the alpha form of the pigment on a suitable Appl. No.: 366,395

US. Cl

Int. Cl

Field of Search OPTICAL DENSITY Primary E.\'aminerHarry I. Moatz OSullivan; John H. Faro 5 7 ABSTRACT materials in electrophotography.

28 Claims, 2 Drawing Figures ZINC PHTHALOCYANINE ORIGINAL FILM POLYMORPH THERMAL CONVERTED FILM (x POLYMORPH) O WAVELENGTH A Sept. 2, 1975 Attorney, Agent, or Firm-James J. Ralabate; James P.

Process for direct alpha to X phase conversion of metal containing phthalocyanines. In this process, the

substrate followed by in situ conversion of this deposit by controlled heating. The X form of metal containing phthalocyanines are known to possess good electrophotographic speed, and, thus, can be used either alone or in combination with other photoconductive PATENTEU 2 975 FIG.

OPTICAL DENSITY ZINC PHTHALOCYANINE ORIGINAL FILM a POLYMORPH THERMAL CONVERTED FILM (x POLYMORPH) l l l l O WAVELENGTH (A) COBALT PHTHALOCYANINE ORIGINAL FILM I POLYMORPH THERMAL \CONVERTED FILM (x POLYMORPH I l l I l WAVELENGTH DIRECT ALPHA TO X PHASE CONVERSION OF METAL CONTAINING PHTl-IALOCYANINE BACKGROUND OF THE INVENTION 1. Field of the lnvention This invention relates to a process for preparation of electrophotographic pigments and the use of such pigments in electrophotographic imaging elements and methods. More specifically, this invention provides a novel route for the preparation of the X polymorph of metal containing phthalocyanines from the alpha form of these pigments.

2. Description of the Prior Art The formation and development of images on the imaging surface of photoconductive materials by electrostatic means is well-known. The best known of the commercial processes, more commonly known as xerography, involves forming a latent electrostatic image on an imaging surface of an imaging member by first uniformly electrostatically charging the surface of the imaging member in the dark and then exposing this electrostatically charged surface to a light and shadow image. The light struck areas of the imaging layer are thus rendered conductive and the electrostatic charge selectively dissipated in these irradiated areas. After the photoconductor is exposed, the latent electrostatic image on this image bearing surface is rendered visible by development with a finely divided colored electroscopic powder material, known in the art as toner". This toner will be principally attracted to those areas on the image bearing surface which retain the electrostatic charge and thus form a visible powder image.

The developed image can then be read or permanently affixed to the photoconductor in the event that the imaging layer is not to be reused. This latter practice is usually followed with respect to the binder-type photoconductive films where the photoconductive layer is an integral part of the finished copy.

1n so-called plain paper" copying systems, the latent image can be developed on the imaging surface ofa reusable photoconductor or transferred to another surface, such as a sheet of paper, and thereafter devel oped. When the latent image is developed on the imaging surface of a reusable photoconductor, it is subsequently transferred to another substrate and then permanently affixed thereto. Any one of a variety of wellknown techniques can be used to permanently affix the toner image to the copy sheet, including overcoating with transparent films, and solvent or thermal fusion of the toner particles to the supportive substrate.

In the above plain paper copying systems, the materi als used in the photoconductive layer should preferably be capable of rapid switching from insulative to conductive to insulative state in order to permit cyclic use of the imaging layer. The failure of the photoconductive material to return to its relative insulative state prior to the succeeding charging sequence will result in an increase in the rate of dark decay of the photoconductor. This phenomenon, commonly referred to in the art as fatigue, has in the past been avoided by the selection of photoconductive materials possessing rapid switching capacity. Typical of the materials suitable for use in such a rapidly cycling imaging system include anthracene, sulfur, selenium and mixtures thereof (US. Pat. No. 2,297,691 selenium being preferred because of its superior photosensitivity.

In addition to anthracene, other organic compounds such as phthalocyanine pigments, are also reportedly useful in electrophotography, see for example US. Pat. No. 3,594,163. These pigments can generally be classified into two major subgroups; the metal-free phthalocyanines and the metal-containing phthalocyanines. X-ray diffraction studies and/or infrared spectral analysis of these pigments indicate that phthalocyanines also exist in at least two different polymorphic forms; they being designated alpha and beta (listed in order of increasing stability). In addition to these well-known forms of the metal-free and metal-containing phthalocyanines, additional polymorphs of the metalcontaining phthalocyanines have also been recently reported, US. Pat. Nos. 3,051,721 (R form); 3,160,635 (delta form); and 3,150,150 (delta form).

More recently, an additional polymorph of the metalfree and metal-containing phthalocyanine pigments has been disclosed. This polymorph, being designated the X form, is described and methods for its preparation contained in US. Pat. Nos. Re. 27,1 17; 3,657,272; and 3,594,163. Comparative evaluation of the various forms of phthalocyanine pigments for use in electrophotography has revealed the X form to be preferred because of its superior electrophotographic speed.

The potential use of this polymorphic form of phthalocyanine pigments in electrophotographic systems imposes stringent requirements on the purity of this material. It is, therefore, imperative that the techniques employed in synthesis of this form of pigment insure that the resulting product be free of impurities and/or other contaminants which can interfere with the electronic requirements of an electrophotographic imaging system.

Until recently, phthalocyanines have been prepared almost exclusively for use as a pigment, where color, tinctorial strength, light fastness, dispersability, etc. are prime considerations and the purity of the pigment being of only incidential importance. The reported methods for synthesis of these compounds very often introduce metals and/or other complex organic materials into the pigment which are very difficult to remove; see Moser and Thomas, Phthalocyanine Compounds. Reinhold Publishing Co., pp. 104 189. Two of the more common methods used in the manufacture of phthalocyanine pigments generally involve 1 indirect formation of the pigment from an acid and a metal phthalocyanine containing a replaceable metal and (2 direct synthesis from phthalonitrile.

Accordingly, it is, the object of this invention to pro vide a process for preparation of the X form of metal containing phthalocyanines substantially free of the contaminants and/or impurities associated with its preparation by more conventional prior art techniques.

More specifically, it is the principal object of this in vention to provide a process for the preparation of the X form of metal containing phthalocyanines from their corresponding alpha polymorph.

It is another of the objects of this invention to provide a process which is directive for the synthesis of the X form of metal containing phthalocyanines.

It is yet another object of this invention to provide a process which is directive for the preparation of the X form of metal containing phthalocyanines from their corresponding alpha polymorph.

It is yet a further object of this invention to provide a process for the preparation of the X form of metal containing phthalocyanines in thin compact films.

SUMMARY OF THE INVENTION The above and related objects are achieved by providing a process for the direct synthesis of the X form of metal containing phthalocyanines from their corresponding alpha polymorph. This process comprises providing a substrate having deposited thereon at least one alpha metal containing phthalocyanine pigment; said deposit having a thickness of up to about 1400 A. This deposit is at least partially converted directly to the X form by heating at a rate in excess of from about C per minute to a temperature in the range of from about 220 to about 450C. In the preferred embodiments of this invention, the alpha metal containing phthalocyanine deposit forms a thin compact film overlying at least one surface of the substrate. The average thickness of the alpha metal containing phthalocyanine deposit used in this process should preferably be less than about 1300 A and thermal conversion to the X polymorph carried out by heating at about 60C per minute to a temperature in the range of from about 330 to about 390C.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a graphical illustration of the absorption spectrum of a vacuum deposited film of the alpha polymorph of zinc phthalocyanine and the absorption spectrum of this same film after in situ thermal conversion to its corresponding X polymorph.

FIG. 2 is a graphical illustration of the absorption spectrum of a vacuum deposited film of the alpha polymorph of cobalt phthalocyanine and the absorption spectrum of this same film after in situ thermal conversion to its corresponding X polymorph.

DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS According to the process of this invention, an alpha metal containing phthalocyanine is deposited on a substrate material and thereafter thermally converted by controlled heating to its corresponding X polymorph. Many of the metal containing phthalocyanines which can be used in the process of this invention are readily commercially available or where not so available can be prepared by any of the conventional techniques described in the technical literature; see for example Chapter 4 of the previously reference Moser and Thomas publication. Among the metals forming known phthalocyanine derivatives which can be used in this process include Group I metals such as lithium, sodium, potassium, copper and silver; Group II metals such as beryllium, magnesium, calcium, zinc, cadmium, barium and mercury; Group III metals such as aluminum, gallium, indium, lanthanum, neodymium, samarium, europium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium and lutecium; Group IV metals such as titanium, tin, hafnium, lead and thorium; Group V metals such as vanadium and antimony; Group VI metals such as chromium, molybdenum and uranium; Group Vll metals such as manganese; and Group VIII metals such as iron, cobalt, nickel, rhodium, palladium, osmium, platinum. Especially preferred metal containing phthalocyanines useful in this process are the alpha and beta froms of copper, cobalt, zinc and nickel phthalocyanines. Prior to deposition of the phthalocyanine on the substrate it should be substantially free of impurities. For example, where the phthalocyanine is prepared directly from phthalonitrile, residual phthalonitrile can be readily removed by washing the phthalocyanine with acetone.

The metal containing phthalocyanine can then be de posited on an appropriate substrate by standard vapor deposition techniques. For example, in such procedures a measured quantity of alpha or beta metal containing phthalocyanine is placed in an open container or boat, the boat placed in a vacuum deposition chamber, a substrate positioned above the boat, the chamber sealed and evacuated to a pressure of less than 10" Torr. The temperature on the boat is then increased to about 400C whereupon the phthalocyanine sublimes and deposits on the substrate. The quantity of the deposition is monitored and upon obtaining the desired amount of alpha metal containing phthalocyanine on said substrate, deposition is terminated by interposition of a shutter between the substrate and the boat. The substrate upon which the alpha metal containing phthalocyanine is deposited is maintained at ambient temperatures (approximately 20C) during such deposition. The form of the deposit on the substrate will vary with the extent of such deposition. Ordinarily, where the deposition is terminated within a few seconds after the alphs metal containing phthalocyanine begins to collect upon the substrate, the deposit may appear as a discontinuous coating. On the other hand, where the deposition is allowed to proceed for about a minute the deposit will appear as a thin compact film. The thickness of such deposition is critical to the process of this invention and must be maintained within previously prescribed limits in order to insure the direct alpha to X phase conversion of the phthalocyanine deposit.

The precise chemical composition and geometry of the substrate used in the condensation of the alpha metal-free phthalocyanine does not appear to be critical, provided, that it is inert toward the alpha metal containing phthalocyanine and its corresponding X polymorph and thermally stable during the heating phase of this process. In the preferred embodiments of this invention, it is preferable that the substrate be nonhygroscopic and relatively transparent. Any one of a variety of materials possessing the above characteristics are suitable for use as substrates in this process; typical of such materials include quartz, tin oxide coated glass (NESA glass) and select plastic films (e.g., poly( N-vinylcarbazole The exposed surface of the alpha metal containing phthalocyanine deposit is then isolated or confined so as to insure the maintanence of a vapor pressure equilibrium between the deposit and the vapors emenating from said deposit during thermal treatment and yet preclude substantial evaporation of the deposit from the substrate during in situ thermal conversion to the X- polymorph. This confinement of the deposit can be achieved by simply placing a plate in contact with the deposit and maintaining this sandwich-like structure during the thermal treatment phase of this process. The composition of this plate is not believed to be critical, and good results have been obtained using materials similar to those employed as substrates. Of course, the physical geometry of the plate should be such as to afford maximum confinement of the deposit on the substrate.

Both the rate of heating and the temperature to which the deposit is heated are critical in determining the direction and extent of conversion of the alpha metal containing phthalocyanine. For example, when such alpha metal containing phthalocyanine deposits are heated at a rate in excess of from about to about 60C per minute to a temperature in the range of from about 220 to about 450C direct conversion of the deposit to the X polymorph is observed. This conversion is manifest by a change in color and a transformation in the apparently structureless character of the deposit to one having a fine uniform grain. Where the rate of heating is below about 10C per minute, substantial quantities of the alpha metal containing phthalocyanine are converted to the corresponding beta polymorph and the deposit takes on a nonuniform appearance. The formation of the beta polymorph within the alpha metal containing phthalocyanine deposit also ap pears to occur at temperatures in the range of from about 420- 450C. At such elevated temperatures, there is a competitive formation of both the X and beta polymorphs and thus, the temperature of such thermal conversion chamber should be maintained below this upper level and perferably in the range of from about 330-390C.

Where the thermal treatment step of this process is carried out in a combined differential thermal analysis-spectrophotometric cell, it is possible to monitor the absorption spectra of the phthalocyanine deposit before and immediately after thermal treatment without removal of the sample from the cell; cell design shown in REVIEW OF SCIENTIFIC INSTRUMENTS, Vol. 41, 1313 I315 (I970). FIGS. 1 & 2 provide graphic illustration of such a shift in absorption spectra resulting from controlled thermal treatment of the alpha polymorphs of zinc and cobalt phthalocyanines films; each having a film thickness of about 800 A.

The X form of metal containing phthalocyanines prepared as described above have rapid photoresponse in the red and near infrared regions of the spectrum and thus, can be used as the photoresponsive medium of an clectrophotographic imaging member. The X form of the pigment can be prepared directly on a conductive substrate, such as tin oxide coated glass, or subsequent to its preparation removed therefrom and dispersed in a film forming insulating resin and sprayed, draw or dip coated on a conductive substrate. The photoresponsive layer containing the X form of the phthalocyanine pigment can be overcoated with an insulating film in order to improve its charge storage characteristics. The rate of dark decay of such members may also be reduced by the interposition of a barrier layer between the photoconductive insulating layer and the conductive substrate. This barrier layer provides a blocking contact thus preventing premature injection of charge carriers from the conductive substrate into the photoconductive insulating medium. The electronic properties of this electrophotographic member require that the image bearing layer thereof have a resistivity in excess of about l0'" ohm centimeters. This insulating quality of the image bearing layer must be maintained even in the presence of an applied electric field.

In addition to the NESA glass type substrate previously disclosed, the X polymorph of metaLfree phthalocyanine can be operatively disposed with respect to any one of a number of conductive substrates such as aluminum, brass, chromium or metalized plastic films.

The electophotographic imaging members prepared from these photoconductive materials and conductive substrates can be used in electrostatographic imaging systems. In such an electrostatographic imaging system, the imaging member comprises an imaging layer (generally containing the photoconductive material) operatively disposed in relation to the conductive substrate. This imaging layer is sensitized in the dark by the application thereto of a uniform electrostatic charge. Among the methods commonly employed for sensitization of this imaging layer include frictional charging or a discharge from a corona electrode. After the imaging layer is sensitized, it is selectively exposed to activating electromagnetic radiation thereby dissipating the charge on the light struck areas of said layer. The remaining charge pattern or latent electrostatic image is rendered visible by development with finely divided colored electroscopic particles, generally referred to in that as toner. This visible toner image can then be fused to the surface of the imaging layer or transferred to a receiving sheet. Fixation of the toner image is generally accomplished by solvent or thermal fusion techniques. Prior to a recycling of the electrostatographic imaging member residual toner particles remaining on the imaging layer are removed by a combination of neutralizing charging and mechanical means.

The Examples which follow further define, describe and illustrate preparation and use of the X polymorph of metalcontaining phthalocyanines. The techniques and equipment used in preparation, analysis and evaluation of the products of this process are standard or as hereinbefore described. Parts and percentages appearing in these Examples are by weight unless otherwise indicated.

EXAMPLE I A measured quantity of the alpha polymorph of copper phthalocyanine is placed in a molybdenum boat, the boat inserted into a vacuum, deposition chamber, and a quartz substrate two inches square by 0.125 inches thick suspended about 16 inches above the boat so that the face of the substrate is perpendicular to the base of the boat. The pressure within the chamber is then reduced to about 10 Torr and the temperature of the boat thereafter increased to about 400C. thus, resulting in the vaporization of the alpha copper phthalocyanine. These vapors rise within the chamer, condense on the substrate and thus form a thin compact, apparently structureless deposit of alpha copper phthalocyanine. Condensation of such vapors is continued until the deposit on the substrate reaches an average film thickness of about 800 A. whereupon a metal shutter is interposed between the boat and the substrate thereby preventing further deposition. Generally, the elapsed time between the initial vaporization of the alpha copper phthalocyanine and the interruption of condensation with the metal shutter is somewhat less than one minute. The vacuum seal of the deposition chamber is then broken, the substrate bearing the alpha copper phthalocyanine deposit removed, a second quartz plate substantially the same as the substrate placed over and in contact with the deposit and the resulting sandwiched-like structure placed within a specially designed differential thermal analysis spectrophotometric cell (of the type referred to previously). Once the sample is secured within the cell, the cell is sealed and the temperature therein increased at a rate of about 60C per minute to a temperature of 330C.

Spectral analysis prior and subsequent to such heat treatment evidences a shift in spectral sensitivity from the alpha to the X polymorph of copper phthalocyanine. The sample can be removed from the cell shortly after heating to the desired temperature or the sample and the cell allowed to cool prior to such removal. The two plates eneasing the sample are separated and the deposit examined under a light microscope at a magnification of 2OOX. The apparently structureless compact film of alpha copper phthalocyanine now possesses a fine grain structure indicating thermal crystallization v during the phase transformation of the copper phthalocyanine from the alpha to the X polymorph.

EXAMPLE II EXAMPLE III The procedure of Example I is repeated, except for the heating of the sample at a rate of 5C per minute to a temperature of 330C. The size and randomness of distribution of crystals within the film is seen to increase dramatically and significant quantities of beta copper phthalocyanine are found to be present within the film.

EXAMPLE IV The procedure of Example I is repeated, except for the heating of the sample to about 420C. Here as in Example Ill, the size and randomness of crystals within the film is seen to increase dramatically and significant quantities of beta copper phthalocyanine are found to be present in the film. Apparently, the period of exposure of the film to such higher temperatures is a factor in determining the relative concentration of the X and beta polymorphs in the film; the more abbreviated the period of heating at such elevated temperatures, the less beta polymorph present in the film.

EXAMPLE V VII Film Predominant Example No. Thickness Physical Appearance Polymeric Form V 1300 A fine uniform grain X polymorph VI 1400 A some increase in X polymorph,

grain size some traees of beta VII 1500 A sharp increase in beta polymorph grain EXAMPLE VIII The procedure of Example I is repeated, except for the failure to cover the sample with a second quartz plate prior to thermal treatment. Spectrophotometric evaluation of the sample indicates direct conversion of the sample from the alpha to the beta polymorph.

EXAMPLE IX The procedure of Example I is repeated, except for the separation of the quartz cover plate from the sample by a 0.01 inch spacer and the maintenance of such separation during thermal treatment. Spectrophotometric evaluation of the sample indicates conversion of the sample directly from the alpha to the beta polymorph.

EXAMPLE X The procedure of Example I is repeated, except for the substitution of a tin oxide coated glass plate (NESA glass) for the quartz substrate. The phthalocyanine product obtained is equivalent to that obtained in Example I.

EXAMPLE XI The procedure of Example I is repeated, except for the substitution of a 50 micron thick film of poly( N- vinylcarbazole) for the quartz substrate. The phthalocyanine product obtained is equivalent to that obtained in Example I.

EXAMPLE XII The X copper phthalocyanine plate of Example X is evaluated for use as an electrostatographic imaging member on a Xerox Model D type copier adapted for acceptance of an imaging member of reduced dimensions. Charging, exposure and development sequences utilized in the copying cycle are standard. The electrostatographic reproductions made with this plate are of acceptable quality.

EXAMPLE XIII The plate prepared as described in Example XI is placed in a vacuum deposition chamber and a 10 micron thick aluminum film vacuum deposited over the layer of X copper phthalocyanine. The resultant plate is removed from the chamber and evaluated for use as an electrostatographic imaging member on a Xerox Model D type copier in the manner described in Example XII. The electrostatographic reproductions made with this plate are superior to those obtained in Example XII.

EXAMPLE XIV The procedures of Example I are repeated except that the vacuum deposition of the alpha copper phthalocyanine is carried out at a pressure of about 30 Torr. As the alpha copper phthalocyanine sublimes it is converted directly to the X form; nucleation and particle growth occurring in the vapor phase. These X copper phthalocyanine particles are collected on an appropriate substrate and subjected to spectrophotometric and light microscopic examination. Such tests confirm that the product is the X polymorph of copper phthalocyanine and that the deposit has a light fluffy microcrystalline structure characteristic of a particulate deposit.

EXAMPLE xv XVIII The procedure of Example I are repeated except for the substitution of the following alpha metal containing phthalocyanine for alpha copper phthalocyanine.

No. Phthalocyanine XV alpha nickel phthalocyanine XVI alpha cobalt phthalocyanine XVII alpha zinc phthalocyanine XVIII alpha lead phthalocyanine EXAMPLE XIX The procedure of Example I is repeated, except for the formation of the alpha copper phthalocyanine deposit on the substrate by sublimation of the beta polymorph of copper phthalocyanine.

EXAMPLE XX XXIII The procedure of Example XIX is repeated except for the substitution of the following beta metal containing phthalocyanines for beta copper phthalocyanine.

No. Phthalocyaninc XX beta nickel phthalocyanine XXI beta cobalt phthalocyanine XXII beta zinc phthalocyanine XXIII bcta lead phthalocyanine EXAMPLE XXIV EXAMPLE XXV XXVIII The procedures of Example XXIV are repeated except for the substitution of the following pigments for X copper phthalocyanine.

N04 Phthalocyaninc XXI X nickel phthalocyanine XXVI X cobalt phthalocyanine XXVII X zinc phthalocyanine XXVIII X lcad phthalocyanine What is claimed is:

l. A process for the direct thermal conversion of the alpha polymorph of at least one metal containing phthalocyanine to the corresponding X polymorph. said process comprising:

a. providing a substrate having deposited thereon at least one alpha metal containing phthalocyanine, said deposit having an average thickness of up to about 1400 Angstrom units;

b. confining said deposit by placing in contact therewith physical means the geometry of said means affording maximum confinement of the deposit on the substrate thereby insuring the maintenance of a vapor pressure equilibrium between the deposit and vapors emanating from said deposit thereby precluding substantial evaporation thereof during thermal conversion to the corresponding X polymorph; and

c. heating said confined deposit at a rate in excess of about 10C per minute to a temperature in the range of from about 220 to 450C so as to effect direct in situ conversion of at least some of the alpha metal containing phthalocyanine to its corresponding X polymorph.

2. The process of claim 1, wherein the deposit of alpha metal containing phthalocyanine has an average thickness of up to about 1300 A.

3. The process of claim 1, wherein said deposit is heated at a rate ranging from in excess of about l0C per minute to about 60C per minute.

4. The process of claim 1, wherein said deposit is heated to a temperature in the range of from about 220 to about 390C.

5. The process of claim 1, wherein the alpha metal containing pthalocyanine deposit is supported on a quartz substrate.

6. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit is supported on a conductive substrate.

7. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit is supported on a tin oxide coated glass substrate.

8. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit is supported on a photoconductive substrate.

9. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit is supported on a film comprising poly( N-vinylcarbazole).

10. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit comprises alpha copper phthalocyanine.

11. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit comprises alpha cobalt phthalocyanine.

12. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit comprises alpha zinc phthalocyanine.

13. The process of claim I, wherein the alpha metal containing phthalocyanine deposit comprises alpha lead phthalocyanine.

14. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit comprises alpha nickel phthalocyanine.

15. A process for the direct thermal conversion of the alpha polymorph of at least one metal containing phthalocyanine to the corresponding X polymorph, said process comprising:

a. providing a substrate having deposited thereon at least one alpha metal containing phthalocyanine, said deposit having an average thickness of up to about I400 Angstrom units;

b. confining said deposit by placing in contact therewith a plate-like member, the physical geometry of said member affording maximum confinement of the deposit on the substrate thereby insuring the maintenance of a vapor pressure equilibrium between the deposit and vapors eminating from said deposit thus precluding substantial evaporation thereof during thermal conversion to the X poly morph; and

c. heating said confined deposit at a rate in excess of about C per minute to a temperature in the range of from about 220 to about 450C so as to effect direct in situ conversion of at least some of the alpha metal containing phthalocyanine to its corresponding X polymorph.

16. The process of claim 15, wherein the deposit of alpha metal containing phthalocyanine has an average thickness of up to about 1300 A.

17. The process of claim 15, wherein said deposit is heated at a rate ranging from in excess of about lOC per minute to about 6OC per minute.

18. The process of claim 15, wherein said deposit is heated to a temperature in the range of from about 220 to about 390C.

19. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit is supported on a quartz substrate.

20. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit is supported on a conductive substrate.

21. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit is supported on a tin oxide coated glass substrate.

22. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit is supported on a photoconductive substrate.

23 The process of claim 15, wherein the alpha metal containing phthalocyanine deposit is supported on a film comprising poly( N-vinylcarbazole).

24. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit comprises alpha copper phthalocyanine.

25. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit comprises alpha cobalt phthalocyanine.

26. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit comprises alpha zinc phthalocyanine.

27. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit comprises alpha lead phthalocyanine.

28. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit comprises alpha nickel phthalocyanine. 

1. A PROCESS FOR THE THERMAL CONVERSION OF THE ALPHA POLYMORPH OF AT LEAST ONE METAL CONTAINING PHTHALOCYANINE TO THE CORRESPONDING X POLYMORPH, SAID PROCESS COMPRISING: A. PROVIDING A SUBSTRATE HAVING DEPOSITED THEREON AT LEAST ONE ALPHA METAL CONTAINING PHTHALOCYANINE, SAID DEPOSIT HAVING AN AVERAGE THICKNESS OF UP TO ABOUT 1400 ANGSTROM UNITS, B. CONFINING SAID DEPOSIT BY PLACING IN CONTACT THEREWITH PHYSICAL MEANS THE GEOMETRY OF SAID MEANS AFFORDING MAXIMUM CONFINEMENT OF THE DEPOSIT ON THE SUBSTRATE THEREBY INSURING THE MAINTENANCE OF A VAPOR PRESSURE
 2. The process of claim 1, wherein the deposit of alpha metal containing phthalocyanine has an average thickness of up to about 1300 A.
 3. The process of claim 1, wherein said deposit is heated at a rate ranging from in excess of about 10C* per minute to about 60C* per minute.
 4. The process of claim 1, wherein said deposit is heated to a temperature in the range of from about 220* to about 390C*.
 5. The process of claim 1, wherein the alpha metal containing pthalocyanine deposit is supported on a quartz substrate.
 6. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit is supported on a conductive substrate.
 7. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit is supported on a tin oxide coated glass substrate.
 8. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit is supported on a photoconductive substrate.
 9. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit is supported on a film comprising poly(N-vinylcarbazole).
 10. The process of claiM 1, wherein the alpha metal containing phthalocyanine deposit comprises alpha copper phthalocyanine.
 11. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit comprises alpha cobalt phthalocyanine.
 12. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit comprises alpha zinc phthalocyanine.
 13. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit comprises alpha lead phthalocyanine.
 14. The process of claim 1, wherein the alpha metal containing phthalocyanine deposit comprises alpha nickel phthalocyanine.
 15. A process for the direct thermal conversion of the alpha polymorph of at least one metal containing phthalocyanine to the corresponding X polymorph, said process comprising: a. providing a substrate having deposited thereon at least one alpha metal containing phthalocyanine, said deposit having an average thickness of up to about 1400 Angstrom units; b. confining said deposit by placing in contact therewith a plate-like member, the physical geometry of said member affording maximum confinement of the deposit on the substrate thereby insuring the maintenance of a vapor pressure equilibrium between the deposit and vapors eminating from said deposit thus precluding substantial evaporation thereof during thermal conversion to the X polymorph; and c. heating said confined deposit at a rate in excess of about 10C* per minute to a temperature in the range of from about 220* to about 450C* so as to effect direct in situ conversion of at least some of the alpha metal containing phthalocyanine to its corresponding X polymorph.
 16. The process of claim 15, wherein the deposit of alpha metal containing phthalocyanine has an average thickness of up to about 1300 A.
 17. The process of claim 15, wherein said deposit is heated at a rate ranging from in excess of about 10C* per minute to about 60C* per minute.
 18. The process of claim 15, wherein said deposit is heated to a temperature in the range of from about 220* to about 390*C.
 19. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit is supported on a quartz substrate.
 20. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit is supported on a conductive substrate.
 21. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit is supported on a tin oxide coated glass substrate.
 22. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit is supported on a photoconductive substrate.
 23. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit is supported on a film comprising poly(N-vinylcarbazole).
 24. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit comprises alpha copper phthalocyanine.
 25. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit comprises alpha cobalt phthalocyanine.
 26. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit comprises alpha zinc phthalocyanine.
 27. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit comprises alpha lead phthalocyanine.
 28. The process of claim 15, wherein the alpha metal containing phthalocyanine deposit comprises alpha nickel phthalocyanine. 